These are the diamond
-shaped tags you see on vehicle
s carrying chemicals and at chemical facilities. The standard for these tags comes from the National Fire Protection Association
and are designed to provide important information to firefighter
s and other rescue
crews in the event of a fire
or other emergency
They are divided into 4 smaller colored dimonds, as follows:
The health, flammability, and reactivity sections each have a number from 0 to 4, which represents the danger levels according to a system similar to, but not identical to, the HMIS ratings
. In particular, the HMIS ratings are intended for employee
safety and so the health ratings consider long-term effect
s, while the NFPA ratings do not.
The special code area may show a W in the case of chemicals that are highly reactive with water, or OX for the presence of oxidizing agents, or both.